1. Field of the Invention
The present invention relates to a display device, and particularly, to a display device in which a bezel is minimized by overlapping circuit lines in an outer edge region with an insulating layer interposed therebetween and directly connecting thin film transistors (TFTs) with the circuit lines.
2. Discussion of Background Art
Liquid crystal displays (LCDs) in related art can display an image by adjusting light transmittance of a liquid crystal having dielectric anisotropy using an electric field. An LCD device can include a liquid crystal panel in which pixel regions are arranged in a matrix form and a driving circuit for driving the liquid crystal panel.
The liquid crystal panel includes first and second substrates attached to each other and a liquid crystal layer formed therebetween. A plurality of gate lines and a plurality of data lines can be arranged to cross each other perpendicularly to define pixel regions. A pixel electrode is formed in each pixel region, and a thin film transistor (TFT) is formed at each crossing of a gate line and a data line. A TFT is turned on according to a scan signal of a gate line to apply a data signal of a data line to each pixel electrode to drive the liquid crystal layer.
A black matrix blocking light transmission in a region other than the pixel region and a color filter layer formed in each pixel region to implement an actual color are disposed on the second substrate.
The driving circuit can include a gate driver that drivers the plurality of gate lines, a data driver that drives the plurality of data lines, a timing controller that supplies a control signal for controlling the gate driver and the data driver, a data signal, and the like. The gate driver includes a shift register to sequentially output scan pulses respectively to gate lines.
The shift register includes a plurality of stages dependently connected to each other. The plurality of stages sequentially output the scan pulses to sequentially scan the gate lines of the liquid crystal panel. Among the plurality of stages, a first stage receives a start signal, as a trigger signal, from the timing controller, and the other stages, excluding the first stage, receive an output signal, as a trigger signal, from the first stage (a stage in front of them). Each of the plurality of stages receives at least one clock pulse among a plurality of clock pulses each having a sequential phase difference. Accordingly, scan pulses are sequentially output from the first stage to the final stage.
The gate driver can include a gate driver integrated circuit (IC) in which the shift register is installed. The gate driver IC can be provided and connected to a gate line pad of the liquid crystal panel using a TCP process, for example. The data driver can use a data driver IC and a gate driver can form, via a gate-in-panel (GIP) technique, a shift register on an LCD device to reduce material cost, the number of processes, and a process time.
FIG. 1 is a plan view of a related art LCD device having a GIP structure. The LCD device can have a GIP structure, a first substrate 1, and a second substrate 2. The first substrate 1 and the second substrate 2 are attached together using a sealant 10 with a predetermined space maintained therebetween. Here, the first substrate 1 is formed to be larger than the second substrate 2 to form a non-display region in which a data driver, for example, can be mounted. A display region is formed at an inner side based on the sealant 10, with which the first substrate 1 and the second substrate 2 are attached.
The display region of the attached first and second substrates 1 and 2 is divided into an active region A/A and a dummy region D. A gate line, a data line, a pixel electrode, and a TFT are formed in the active region A/A of the first substrate 1. A black matrix layer and a color filter layer are formed in the active region A/A of the second substrate 2.
The dummy region D of the first substrate 1 can include a GIP gate driver 3, a GIP dummy gate driver 4, a ground 11, control signal lines 12, a GIP circuit 13 configured as a shift register, and a common line 14. The gate driver 3, the GIP dummy gate driver 4, a ground 11, and the control signal lines 12 are for applying various signals such as a clock signal, an enable signal, a start signal, or a common voltage, for example, which are output from a timing controller to the GIP gate driver 3 and the GIP dummy gate driver 4. A black matrix formed to block light transmission to the dummy region D can be formed in the dummy region D of the second substrate 2.
A size of a bezel in related art including a dummy region can be minimized to reduce a size of a display device and obtain a fine appearance, while maintaining a screen with the same size.
FIG. 2 is an enlarged plan view of a region ‘A’ in FIG. 1. The LCD device having a GIP structure includes the ground 11, the control signal lines 12, the shift GIP circuit 13, and the common line 15 disposed in the dummy region D. The dummy region D needs to have a predetermined width d1 or greater. Thus, a limitation in reducing the area of the dummy region D results in a limitation in reducing the bezel area, making it impossible to manufacture an LCD device having a very small (narrow) bezel area.
A TFT 23 is formed in the shift GIP circuit 13 and a control signal from the control signal lines 12 is input to the TFT 23. The TFT 23 is connected to the signal lines 12 through a metal line 24. Here, to connect the plurality of control signal lines 12 by the metal line 24, the TFT 23 is electrically insulated from the crossing control signal lines 12 by an insulating layer formed on the control signal lines 12. The metal line 24 is formed on the insulating layer, and a contact hole is subsequently formed on a source electrode of the TFT 23 to electrically connect the control signal lines 12 and the TFT 23.
Thus, the related art LCD device having a GIP structure has a complicated structure and processes, increasing manufacturing costs and a probability of generating a defect due to the complicated structure.